Dual ratio constant mesh gearbox

Abstract

A dual ratio constant-mesh gearbox is provided that is suitable for use with an automobile, and particularly well-suited for an electric vehicle. The gearbox, which may be configured either as a manual or automatic gearbox, utilizes a planetary gear set and a pair of clutches to shift between under drive and direct drive modes.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to a vehicle and, more particularly, to a dual speed gearbox suitable for use with an electric motor.BACKGROUND OF THE INVENTION[0002]In a typical electric vehicle a single speed gearbox is used between the traction motor and the differential. The ability to use a single speed gearbox rather than the multi-speed gearbox required in a conventional vehicle is the result of the wide useful operating range, both in terms of power and torque, of an electric motor versus that of an internal combustion engine.[0003]While a single speed gearbox may be used with an electric vehicle, its use is not without drawbacks. For example, because of the maximum speed limit of the motor and the requirement in a high performance car to reach a certain top speed, the gear ratio is typically chosen to be longer than what would be optimal to provide crisp initial acceleration from a standstill. Additionally, due to torque ripple and vibrat...

AI Technical Summary

Benefits of technology

The present invention provides a dual ratio constant-mesh gearbox suitable for electric vehicles. The gearbox includes a housing, an input drive shaft, an output drive shaft, and a set of planetary gears. The gearbox also includes a clutch member that can be translated between a locked position and an unlocked position. The clutch member is coupled to a set of planetary gears and a sun gear. The clutch member has a first surface in contact with the planetary gears and a second position in which it is no longer in contact with the planetary gears. The clutch member is biased towards the locked position. The gearbox operates in a direct drive mode when the clutch member is in the locked position and in an under drive mode when the clutch member is in the unlocked position. The gearbox is suitable for electric vehicles and can provide smooth shifting between the two modes.

Problems solved by technology

Additionally, due to torque ripple and vibrations, motor torque may be limited at very low rotating speeds.

As a result, initial acceleration from a standstill in a typical electric vehicle is typically more sluggish than what would be expected given the drivetrain's characteristics.

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